ftrace instrumentation for RT tasks

From: Gregory Haskins <ghaskins@novell.com>

Signed-off-by: Gregory Haskins <ghaskins@novell.com>
---

 arch/x86/kernel/smp.c |    2 ++
 include/linux/sched.h |    6 ++++++
 kernel/sched.c        |    3 +++
 kernel/sched_rt.c     |   10 ++++++++++
 4 files changed, 21 insertions(+), 0 deletions(-)


diff --git a/arch/x86/kernel/smp.c b/arch/x86/kernel/smp.c
index e6faa33..468abeb 100644
--- a/arch/x86/kernel/smp.c
+++ b/arch/x86/kernel/smp.c
@@ -118,6 +118,7 @@ static void native_smp_send_reschedule(int cpu)
 		WARN_ON(1);
 		return;
 	}
+	ftrace_printk("cpu %d\n", cpu);
 	send_IPI_mask(cpumask_of(cpu), RESCHEDULE_VECTOR);
 }
 
@@ -171,6 +172,7 @@ static void native_smp_send_stop(void)
  */
 void smp_reschedule_interrupt(struct pt_regs *regs)
 {
+	ftrace_printk("NEEDS_RESCHED\n");
 	ack_APIC_irq();
 	inc_irq_stat(irq_resched_count);
 }
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 4cae9b8..a320692 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2094,8 +2094,14 @@ static inline int test_tsk_thread_flag(struct task_struct *tsk, int flag)
 	return test_ti_thread_flag(task_thread_info(tsk), flag);
 }
 
+# define ftrace_printk(fmt...) __ftrace_printk(_THIS_IP_, fmt)
+extern int
+__ftrace_printk(unsigned long ip, const char *fmt, ...)
+	__attribute__ ((format (printf, 2, 3)));
+
 static inline void set_tsk_need_resched(struct task_struct *tsk)
 {
+	ftrace_printk("%s/%d\n", tsk->comm, tsk->pid);
 	set_tsk_thread_flag(tsk,TIF_NEED_RESCHED);
 }
 
diff --git a/kernel/sched.c b/kernel/sched.c
index 52bbf1c..d55fcf1 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -1874,6 +1874,9 @@ void set_task_cpu(struct task_struct *p, unsigned int new_cpu)
 		      *new_cfsrq = cpu_cfs_rq(old_cfsrq, new_cpu);
 	u64 clock_offset;
 
+	ftrace_printk("migrate %s/%d [%d] -> [%d]\n",
+		      p->comm, p->pid, task_cpu(p), new_cpu);
+
 	clock_offset = old_rq->clock - new_rq->clock;
 
 	trace_sched_migrate_task(p, task_cpu(p), new_cpu);
diff --git a/kernel/sched_rt.c b/kernel/sched_rt.c
index 954e1a8..59cf64b 100644
--- a/kernel/sched_rt.c
+++ b/kernel/sched_rt.c
@@ -1102,6 +1102,8 @@ static int push_rt_task(struct rq *rq)
 	if (!next_task)
 		return 0;
 
+	ftrace_printk("attempting push\n");
+
  retry:
 	if (unlikely(next_task == rq->curr)) {
 		WARN_ON(1);
@@ -1139,6 +1141,8 @@ static int push_rt_task(struct rq *rq)
 		goto out;
 	}
 
+	ftrace_printk("%s/%d\n", next_task->comm, next_task->pid);
+
 	deactivate_task(rq, next_task, 0);
 	set_task_cpu(next_task, lowest_rq->cpu);
 	activate_task(lowest_rq, next_task, 0);
@@ -1180,6 +1184,8 @@ static int pull_rt_task(struct rq *this_rq)
 	if (likely(!rt_overloaded(this_rq)))
 		return 0;
 
+	ftrace_printk("attempting pull\n");
+
 	next = pick_next_task_rt(this_rq);
 
 	for_each_cpu(cpu, this_rq->rd->rto_mask) {
@@ -1234,6 +1240,10 @@ static int pull_rt_task(struct rq *this_rq)
 
 			ret = 1;
 
+			ftrace_printk("pull %s/%d [%d] -> [%d]\n",
+				      p->comm, p->pid,
+				      src_rq->cpu, this_rq->cpu);
+
 			deactivate_task(src_rq, p, 0);
 			set_task_cpu(p, this_cpu);
 			activate_task(this_rq, p, 0);